I bought detachable sideplates, a short sissy bar, and a short sissy bar pad. Everything fits fine, save for the sissy bar itself. It has 4 holes that line up with the 4 holes on the side-plates, and I was supplied with 4 button head cap screws (allen). However, what do the screws attach to? It seems to me like the sissy bar holes should be threaded, but they aren't. What am I missing?

I just installed a rigid mount short sissy bar and it came with bolts AND nuts. Trip to Home Depot? However, the bolts were touching the seat, so I flipped them around and now have to buy chrome acorn bolts to make it look right.

I don't think that the back side is accessible for any nuts...I may need to post pictures when I get home this evening. I could maybe squeeze a really narrow nut between the non-show side of the side-plate and the bar itself? Or should the bolt go completely through the side plate? If so, then I can see where the nut would fit on the inside...but my side-plates have no holes.

I think you lost your nuts. I have two different types. My rigid mount screws into the threaded sissybar, my new detachable, the bolts go all the way through with chrome castle nuts with self locking nylon inserts. It sounds like they just didn`t send the proper hardware kit to me.